Compulsive hoarding, considered a form of obsessive-compulsive disorder (OCD), includes symptoms of excessive acquisition (buying, acquiring free things), difficulty discarding, and excessive clutter. It is resistant to both pharmacological (serotonergic medications) and psychotherapeutic interventions (exposure and response prevention) that have been demonstrated effective for other symptoms of OCD. The proposed project aims to develop and test a multi-component psychosocial treatment based on identified psychopathology features of compulsive hoarding and on a cognitive behavioral model of this complex syndrome. It also aims to pilot test the manualized therapy to determine the effect size of the treatment based on comparison to waitlist control. A cognitive-behavioral treatment (CBT) manual investigators have employed in pilot studies of small samples will be revised and expanded in Phase 1, particularly with regard to elaboration of motivational and relapse prevention methods. In Phase 2, two therapists at research-based anxiety clinic settings in Boston and Hartford will be trained to use the revised manual to treat 12 clients for whom compulsive hoarding is their main problem. During this phase, treatment will be flexibly applied allowing for variations in treatment duration and choice of techniques within symptom-focused modules. Investigators will closely supervise therapists by listening to audiotapes of all treatment sessions. Measures of therapist adherence and competence developed in Phase 1 will be refined and tested by investigators in Phase 2. Process and outcome experience with clients during the second phase will guide further revisions to the manual and to adherence/competence measures, as well as the decision about the optimal length of treatment for a pilot study with a larger sample. In Phase 3, 40 clients with primary hoarding symptoms will be treated with a fixed duration therapy at the same two sites. Clients will be randomly assigned to CBT or to waitlist (WL) control followed by active treatment. Independent assessors will assess adherence and competence from audiotaped therapy sessions using revised instruments. Outcomes will be assessed with psychometrically sound measures of compulsive hoarding symptoms and related psychopathology to yield effect size estimates suitable for future large scale controlled trials. Predictors of outcome will be examined. [unreadable] [unreadable]